Clay/AMO complex and derivative thereof and method for producing the same

ABSTRACT

The present invention discloses a clay/amine complex which is an excellent surfactant and a good reinforcing agent of polymers. The complex of the present invention can be produced by modifying layered inorganic silicate clay such as montomorillonite, with an intercalating agent, AMO (amine terminal-mannich oligomer). The AMO can be obtained by polymerizing polyoxyalkylene amine having molecular weight over 1000, p-cresol and formaldehyde. The present invention further discloses a nanosilica plate, which can be obtained by extracting the above complex with a hydroxide or a chloride of alkali metal or alkaline-earth metal, and consequently, the AMO intercalating agent can be recycled for reusing.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a silicate clay/AMO complex anda derivative thereof and, more particularly, to a silicate clay/AMOcomplex and a derivative thereof wherein the AMO (Amineterminating-Mannich Oligomer, prepared from Mannich reaction ofp-cresol) serves as an intercalating agent. The present invention alsorelates to a method for producing the clay/AMO complex and thederivative thereof. Alternatively, the layered silicates are delaminatedinto individual silicate plate and AMO is extracted out and recycled.

[0003] 2. Related Prior Art

[0004] Currently, inorganic/organic polymer complex materials under ananoscale regime are one of the most significant materials, and thushave been widely investigated and developed. Such complex materials aredual-phased wherein at least one phase is dispersed under a nanoscaleregime. Accordingly, compatibility between the two phases, for example,clay and polymers, is always essential for the nanoscale dispersion.

[0005] For layered silicate clay which is hydrophilic and immisciblewith most organic solvents, the interlayer distances can be enlarged bymeans of intercalating with organic quaternary ammonium, and thusmonomers are allowed to enter therethrough. The monomers can bepolymerized within the interlayer space to obtain an exfoliatedinorganic/organic polymer complex material. In principle, the distances,enlarged by intercalating agents, are constant and required to be wideenough for monomer or polymer molecules to enter. As for exfoliation,the interlayer distances are irregular and different directions mayoccur in each layer.

[0006] Conventional intercalating agents such as 12-aminolauric acid,hexadecylamine, fatty amine, bis(2-hydroxyethyl) methyl tallow alkylamine and stearylamine, usually have low molecular weights and can beconverted into the corresponding ammonium salts such as quaternarychloride salt, and interlayer distances of the clay can be ionicallyexchanged and hence sterically expanded to a certain degree ofinterlayer spacing.

[0007] Referring to the research of T. J. Pinnavaia (Michigan StateUniversity), intercalating agent CH₃(CH₂)_(n)-NH₃ ⁺ is provided toexchanged with metal ion salts within the layer-structuralmontmorillonite (MMT) in resulting intercalated MMT, which is thendispersed in diglycidyl ether of BPA (such as epoxy resin Shell Epon828)to form a epoxy polymer-clay complex material under a well-dispersednanoscale regime. For such intercalating agent, the interlayer distancescan be enlarged to 18.0 Å. The epoxy resin can then form an epoxy/claymaterial through curing polymerization at 75° C. This reference alsoindicates an improvement in heat distortion temperature. Theintercalating agent performs a rule of monolayer to bilayer, and even topseudo-trimolayer. The interlayer distance ranges between 13.8-18.0 Å,which allow the epoxy resin to enter and polymerize therein, and furtherto exfoliate the layered inorganic matter so that application advantagesof nonomaterials can be achieved.

[0008] Japanese Patent No. 8-22946 discloses the first commercialinorganic/organic polymer complex material under a nanoscale regime,which is developed by Toyota Company. This complex material is producedby dispersing [H₃N⁺(CH₂)₁₁COO⁻]-montmorillonite in Nylon 6, wherein theaminocarboxylic acid is provided as an intercalating agent and thepolymers are formed between layers of the aminoacid intercalated claythrough condensation of caprolactam monomers to Nylon 6 polymer.However, the aminocarboxylic acid intercalating agent is hydrophilic anddoesn't facilitate nonpolar polymers such as polyethylene andpolypropylene, to uniformly disperse in the hydrophilic layeredsilicate. Accordingly, Japanese Patent Publication No. 8-53572 providesother organic onium ions as an intercalating agent to mix with layeredsilicate, which can be uniformly dispersed in molten polyolefin resin.Unfortunately, though the organic onium ions can enlarge the interlayerdistances to certain degree, affinity between the intercalating agentand the polyolefin resin is not enough to exfoliate the layeredsilicate. Further, Japanese Patent Publication No. 10-182892 indicatesthat when blending in a molten mixture containing olefin oligomers withH-bond and polyolefin resin, the organized layered silicate might beindefinitely swelled due to the strong affinity therebetween. However,it's a dilemma whether to increase the oligomers for better dispersingor to decrease the oligomers for better mechanical characteristics.

[0009] Accordingly, there is a need to ameliorate the complexes by meansof providing appropriate intercalating agents which could render theintercalated silicates with a wider interlayer distance and tailoredspacing for more compatible with polymer materials. Furthermore, thewidely opened silicates can be further tailored and used as novelinorganic/organic surfactants, an important industrial application butdeviated from the common nanocomposite usages.

SUMMARY OF THE INVENTION

[0010] An object of the present invention is to provide a layeredsilicate clay/AMO complex and a method for producing the same, wherebythe clay/AMO complex can exhibit excellent interfacial and surfactanteffect and be applied to facilitate emulsion process as well asreinforcing polymers.

[0011] Another object of the present invention is to provide aderivative of the clay/AMO complex and a method for producing the same,whereby nanosilica plates can be obtained through direct exfoliation andthe intercalating agent AMO can be extracted, isolated and recycled forreusing.

[0012] Accordingly, the clay/AMO complex of the present inventionincludes an Amine terminating-Mannich Oligomer (AMO) and layeredinorganic silicate clay, wherein the AMO is a straight-chain polymerformed by polymerizing polyoxyalkylene amine having a molecular weightover 1000, p-cresol and formaldehyde, and the layered inorganic silicateclay is intercalated with the AMO.

[0013] The complex may have a layered structure with interlayerdistances ranging from 20 to 98 Å, or have an exfoliative nanostructure.

[0014] The aforementioned polyoxyalkylene amine can be polyoxypropylenediamine, polyoxyethylene diamine, orpoly(oxyethylene-oxypropylene)diamine, wherein the polyoxypropylenediamine is preferred. The commercial polyoxyalkylene amine includesJeffamine D2000 [poly (propylene glycol) bis (2-aminopropyl ether), Mw2000], Jeffamine D4000 [poly (propylene glycol) bis (2-aminopropylether), Mw 4000], Jeffamine ED2001 [poly(propyleneglycol)-block-poly(ethylene glycol)-block-poly (propylene glycol)bis(2-aminopropyl ether), Mw 2000], T3000 [tri-functional poly(propyleneglycol)-2-aminopropyl ether, Mw 3000], T5000 [tri-functionalpoly(propylene glycol)2-aminopropyl ether, Mw 5000], etc., wherein theJeffamine D2000 is preferred. The Jeffamine series product has formulaeas follows:

[0015] wherein x=33 (Approx. Mw=2000; Jeffamine® D2000); or

[0016] x=68 (Approx. Mw=4000; Jeffamine® D-4000);

[0017] wherein x+z≈5, y≈39.5 (Approx. Mw=2000; Jeffamine® ED-2001).

[0018] The layered inorganic silicate clay used in the present inventionis not restricted, for example, montmorillonite, kaolin, mica and talc.The layered inorganic silicate clay preferably has a cation exchangecapacity (CEC) ranging from 50 meq/100 g to 200 meq/100 g.

[0019] The derivative obtained from the aforementioned clay/AMO complexis in the form of nanosilica plates and can be formed by extracting thecomplex with a hydroxide or a chloride of alkali metal or alkaline-earthmetal, for example, sodium hydroxide, potassium hydroxide, sodiumcarbonate, sodium bicarbonate.

[0020] The method for producing the clay/AMO complex of the presentinvention primarily includes at least one step of intercalating thelayered inorganic silicate clay with the AMO by powerfully stirring at60-180° C. to perform cation exchange reaction; wherein the AMO servesas an intercalating agent. The AMO is preferably acidified with aninorganic acid such as hydrochloric acid to convert amine intoquaternary ammonium salt before performing the cation exchange withclay, and the layered inorganic silicate clay is preferably swelled withwater to allow the silicate layers fill with water as medium. Theinorganic acid is provided to acidify the amino groups of the AMO toform a quaternary ammonium compound and perform cation exchange.Consequently, the pristine clay of hydrophilic nature is modified intohydrophobic and miscible with organic polymers. Furthermore, theinterlayer distances of the clay are enlarged to 20-98 Å so as to allowpolymers easily intercalate therebetween. The reaction scheme is asfollows:

[0021] The aforementioned inorganic acid is not restricted, for example,hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid.

[0022] The temperature for performing cation exchanging is usuallycontrolled at 80-160° C., and preferably at 80-120° C. nanosilica plate.In the method of the present invention, the ratio of the intercalatingagent to the inorganic acid is controlled to generate specificquaternary ammonium compound in a zig-zag stretched form rather than astraight AMO. As a result, the direct exfoliation is obtained and, afterthe extractive separation, the nanosilica plates can be obtained.

[0023] The organic solvent aforementioned can be ether, ketone, ester,nitrile, saturated hydrocarbon, chloric saturated hydrocarbon oraromatic hydrocarbon, for example, tetrahydrofuran, isopropyl ether,methyl tert-butyl ether, methyl isobutyl ketone, acetonitrile, ethylacetate, pentane, hexane, heptane, cyclohexane, dichloromethane,benzene, toluene, dimethylbenzene, chlorobenzene and methoxybenzene.

BRIEF DESCRIPTION OF THE DRAWING

[0024]FIG. 1 shows the interfacial tensions of toluene/water when theMMT/AMO complex is added. The result indicates the surfactancy of thecomplex which exist in the interface of toluene/water in rendering thedecrease of interfacial tension.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In order to explicitly explain the present invention, somepreferred examples are described in detail as the follows. However, itshould be noticed that the scope of the present invention is not limitedto these examples.

[0026] In these examples, montmorillonite (MMT) is used, which isalumino-silicate clay, and has a structural formula including two layersof tetrahedral silicate and one layer of octahedral aluminatherebetween. In general, the primary structure of the MMT includesaverage 10 parallel lamellae and is about 100 Å high with interlayerdistances about 12 Å. The secondary structure of the MMT is about size0.1-10 μ in diameter and can be formed by aggregating hydrophilicsilicate thereof.

[0027] The clay such as MMT may have cation exchange capacity (CEC) in awide range, and preferably within 50-200 meq/100 g. Beyond such a range,the clay is difficult to be swelled because of insufficient ion exchangeor excessive interlayer attraction. The MMT used in the followingexamples is Kunipia F (Na⁺-MMT, CEC=115 meq/100 g). Other materialsinclude p-cresol (ACROS Co., Mw 108, m.p. 31-34° C., b.p. 202° C.), poly(propylene glycol) bis (2-amino propyl ether) (Huntsman Chemical Co.,trademark Jeffamine D2000, Mw 2000), and formaldehyde (ACROS Co., Mw 30,37 wt % aqua solution).

Examples 1-5

[0028] The complexes of the present invention are produced according tosteps of:

[0029] Step 1: Swelling the layered inorganic silicate clay (sodium formof montmorillonite or Na⁺-MMT)

[0030] Na⁺-MMT (5 g) is dispersed in water (1,000 ml, 80° C.) bypowerfully stirring for four hours, and then a stable and uniform slurryin earth color is formed.

[0031] Step 2: Synthesizing the intercalating agent AMO

[0032] P-cresol (5 g, 0.046 mol) and D2000 (185 g, 0.092 mol) are mixedby refluxing in toluene at 90° C. for 3 hours by using a Dean-Starktrap. Formaldehyde solution (37%, 10 g, 0.12 mol) is then added into thesolution and heated to 130° C. for 5 hours. The reaction is stoppedafter removing the generated water before the formation of AMO gel. Bymeasured with GPC, four peaks of Mw 2598, 5842, 9234 and 16952 oligomerscan be observed. Four oligomers are analogs which can be used as suchfor intercalation. The titration values of primary amine, secondaryamine and tertiary amine are 0.37 meq/g, 0.62 meq/g and 0 meq/g,respectively.

[0033] Step 3: Acidifying the intercalating agents

[0034] The intercalating agent AMO (13.5) is dissolved in water, andthen equivalent moles of hydrochloric acid is added into therein at 80°C. to perform acidification for 30 minutes. The molar ratio ofintercalating agent and HCl is varied in controlling the intercalationor exfoliation of MMT.

[0035] Step 4: Intercalating the AMO to the layered inorganic silicateclay

[0036] The acidified AMO is added into the slurry of Step 1 according toratios of Table 1, and then powerfully stirred at 80° C. for 5 hours toperform cation exchange. The mixture is then settled and filtered. Theproduct is dried in a vacuum oven for 24 hours to remove water. The tintsolid, MMT/AMO complex, can be observed. The interlayer distances aredetected with X-ray diffraction and listed in Table 1.

Example 6

[0037] Repeat steps of Example 1, but HCl is added in a different ratioto the MMT as listed in Table 1. The interlayer distance of the productis measured by X-ray diffraction and listed in Table 1.

Comparative Example 1

[0038] Repeat steps of Example 1, but no HCl is provided foracidification. The interlayer distance of the product is measured byX-ray diffraction and listed in Table 1. TABLE 1 Intercalating MMT byusing AMO/HCl at different ratio Interlayer Intercalating IntercalatingAMO:MMT^(a):HCl distance agent/clay^(b) agent/clay^(c) (mole ratio) (Å)(w/w %) (w/w %) Example 1 1:3:3 39.4 48/52 45/55 Example 2 1:2:2 50-5261/39 57/43 Example 3 2:3:3 50-52 66/34 66/34 Example 4 1:1:1 50-5273/27 72/28 Example 5 2:1:1 61   83/17 83/17 Example 6   2:1:0.5Exfoliate 85/15 83/17 Comparative 1:1:0 12   — — Example 1

[0039] As listed in Table 1, the interlayer distances of Examples 1-5are significantly larger than that of MMT without intercalation. InExamples 1-5, it's obvious that the interlayer distances increase whenmore AMO is added. Further, when the ratio of AMO to MMT is up to 2,exfoliation occurs in Example 6 by decreasing the acidifying agent HCl.

[0040] In Examples 1-6, emulsion occurs during reaction and the productemulsion A and the emulsion B are mixed by powerfully stirring at 80° C.for 30 minutes. NaOH solution (5 ml, 5 N) is then added into thesolution and powerfully stirring at 80° C. for 3 hours. Finally, thenanosilica plates dispersed in the lower layer can be collected, andsimultaneously, the AMO in the upper layer can be recycled for reusing.

[0041] The conventional nanomaterial is usually spherical, filmy orcylindrical. The derivative of the clay/AMO complex produced inaccordance with the present invention has high aspect ratio and isplate-shaped.

What is claimed is:
 1. An clay/AMO complex, comprising: an amineterminal-mannich oligomer (AMO) having a straight chain structure formedby polymerizing polyoxyalkylene amine with a molecular weight over 1000,p-cresol and formaldehyde; and layered inorganic silicate clayintercalated with said AMO.
 2. The complex of claim 1, wherein saidpolyoxyalkylene amine is selected from the group consisting ofpolyoxypropylene diamine, polyoxyethylene diamine andpoly(oxyethylene-oxypropylene)diamine adduct.
 3. The complex of claim 1,wherein said polyoxyalkylene amine is polyoxypropylene diamine.
 4. Thecomplex of claim 1, wherein said layered inorganic silicate clay isselected from the group consisting of montmorillonite, kaolin, mica andtalc.
 5. The complex of claim 1, wherein said layered inorganic silicateclay has a cation exchange capacity ranging from 50 meq/100 g to 200meq/100 g.
 6. A nanosilica plate, which is formed by extracting thecomplex of claim 1 with a hydroxide or a chloride of alkali metal oralkaline-earth metal.
 7. The nanosilica plate of claim 8, which isformed by extracting the complex of claim 1 with sodium hydroxide.
 8. Amethod for producing a clay/AMO complex, comprising at least one step ofintercalating layered inorganic silicate clay with an intercalatingagent, amine terminal-mannich oligomer (AMO), by powerfully stirring at60-180° C. to perform cation exchange; wherein said intercalating agentis a straight chain polymer formed by polymerizing polyoxyalkylene aminehaving a molecular weight over 1000, p-cresol and formaldehyde, andpreviously acidified with an inorganic acid, and said layered inorganicsilicate clay previously is previously swelled with water.
 9. The methodof claim 8, wherein said layered inorganic silicate clay is selectedfrom the group consisting of montmorillonite, kaolin, mica and talc. 10.The method of claim 8, wherein said layered inorganic silicate clay hasa cation exchange capacity ranging from 50 to 200 meq/100 g.
 11. Themethod of claim 8, wherein said polyoxyalkylene amine is selected fromthe group consisting of polyoxypropylene diamine, polyoxyethylenediamine, poly(oxyethylene- oxypropylene)diamine adduct.
 12. The methodof claim 8, wherein said polyoxyalkylene amine is polyoxypropylenediamine.
 13. The method of claim 8, wherein said inorganic acid isselected from the group consisting of hydrochloric acid, sulfiric acid,phosphoric acid and nitric acid.
 14. The method of claim 8, wherein saidintercalating agent is mixed with said layered inorganic silicate clayby powerfully stirring at 80-160° C. to perform cation exchange.
 15. Themethod of claim 8, wherein said intercalating agent is mixed with saidlayered inorganic silicate clay by powerfully stirring at 80-120° C. toperform cation exchange.
 16. The method of claim 8, wherein the moleratio of said intercalating agent to said cation exchange capacity ofsaid layered inorganic silicate clay is 1:3-2:1, and the mole ratio ofsaid cation exchange capacity to said inorganic acid is about 1:1,thereby obtaining said complex having a layered structure and interlayerdistances ranging from 20 to 98 Å.
 17. The method of claim 8, whereinthe mole ratio of said intercalating agent to said cation exchangecapacity of said layered inorganic silicate clay is more than 2:1, andthe mole ratio of said cation exchange capacity to said inorganic acidis more than 2:1, thereby obtaining said complex having an exfoliativestructure.
 18. A method for producing a nanosilica plate, comprisingsteps of: A. dissolving said complex of claim 8 in an organic solvent ata predetermined temperature to form an emulsion A; B. dispersing saidlayered inorganic silicate clay in hot water and powerfully stirring toobtain an emulsion B; C. mixing said emulsion A and said emulsion B bypowerfully stirring at a predetermined temperature; D. adding ahydroxide or a chloride of alkali metal or alkaline-earth metal andkeeping powerfully stirring; and E. leaving said mixture static forsettling and obtaining said nanosilica plate dispersed in water.
 19. Themethod of claim 18, wherein said organic solvent is selected from thegroup consisting of ether, ketone, ester, nitrile, saturatedhydrocarbon, chloric saturated hydrocarbon and aromatic hydrocarbon. 20.The method of claim 18, wherein said organic solvent is selected fromthe group consisting of tetrahydrofuran, isopropyl ether, methyltert-butyl ether, methyl isobutyl ketone, ethylnitrile, ethyl acetate,pentane, hexane, heptane, cyclohexane, dichloromethane, benzene,toluene, dimethylbenzene, chlorobenzene and methoxybenzene.
 21. Themethod of claim 18, wherein said hydroxide or chloride of alkali metalor alkaline-earth metal is sodium hydroxide.